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CA 19-9 Unit Converter
Carbohydrate Antigen 19-9 (CA 19-9) is a mucin-glycoprotein tumor marker primarily associated with cancers of the gastrointestinal tract. It is related to the Lewis blood group antigens; individuals who are Lewis-negative (Le a-b-, approx. 5-10% of the population) cannot synthesize CA 19-9 and will have undetectable levels even in the presence of large tumors.
Clinically, CA 19-9 is the gold standard biomarker for Pancreatic Ductal Adenocarcinoma and is also used for biliary tract cancers (cholangiocarcinoma). While it is not recommended for general screening due to low specificity (it can be elevated in pancreatitis, cirrhosis, and cholestasis), it is invaluable for monitoring response to therapy and detecting recurrence. Results are reported in International Units (IU/mL or U/mL), which are interchangeable with the SI unit kU/L.
SI Units
RecommendedUnits per milliliter (Standard Clinical Unit).
Conventional Units
Clinical Context
Reference Range: In healthy adults, CA 19-9 is typically < 37 U/mL.
In pancreatic cancer, levels > 100 U/mL are highly suggestive of malignancy, and extremely high levels (> 1,000 U/mL) often indicate metastatic disease and unresectability. However, transient elevations can occur in benign obstructive jaundice (stones), so testing is best interpreted after biliary drainage. The conversion factor is 1:1 for standard units: 1 U/mL = 1 kU/L = 1 IU/mL.
Clinical References
How to Use This Calculator
Follow these steps to get accurate clinical conversions instantly.
Enter Values
Input your laboratory results into the corresponding unit field (e.g., U/mL). You can use either dot or comma decimals.
Automatic Conversion
The calculator works in real-time. As you type in one field, all other units (like kU/L) are instantly updated.
Verify Units
Check the SI Units section. Note that U/mL and kU/L are numerically identical.
Reset
Use the Clear button to reset all fields before starting a new calculation.
Frequently Asked Questions & Tips
CA 19-9 is defined by its antibody binding reactivity. There is no standard conversion to mass.
Yes, “Units” and “International Units” are used interchangeably for this assay.